1. Field of the Invention
The present invention relates to a power circuit, gate driving circuit and display module, and more particularly, to a power circuit, gate driving circuit and display module which convert a supply voltage step by step without employing any high voltage endurance component.
2. Description of the Prior Art
Please refer to FIG. 1, which is a schematic diagram of a thin film transistor (TFT) LCD monitor 10 of the prior art. The LCD monitor 10 includes an LCD panel 100, a source driver 102, a gate driver 104, a voltage generator 106 and a logic control circuit 116. The LCD panel 100 is composed of two substrates, and space between the substrates is filled with liquid crystal materials. One of the substrates is installed with a plurality of data lines 108, a plurality of scan lines (or gate lines) 110 and a plurality of TFTs 112, and another substrate is installed with a common electrode for providing a common signal Vcom outputted by the voltage generator 106. The TFTs 112 are arranged as a matrix on the LCD panel 100. Accordingly, each data line 108 corresponds to a column of the LCD panel 100, each scan line 110 corresponds to a row of the LCD panel 100, and each TFT 112 corresponds to a pixel. Note that the LCD panel 100 composed of the two substrates can be regarded as an equivalent capacitor 114.
The source driver 102 and the gate driver 104 input signals to the corresponding data lines 108 and scan lines 110 based upon a desired image data, to control whether or not to enable the TFT 112 and a voltage difference between two ends of the equivalent capacitor 114, so as to change alignment of the liquid crystals as well as the penetration amount of light. As a result, the desired image data can be correctly displayed on the LCD panel 100. The logic control circuit 116 is utilized for coordinating the source driver 102 and the gate driver 104, such as calibrating timing of source driving signals on the data lines 108 and scan signals on the scan lines 110, such that the TFTs 112 can be enabled by the scan signals and receive correct image data via the source driving signals at correct time instances.
Based on manufacturing requirements, components of the driving circuits of the LCD monitor 10 are mainly classified into low voltage endurance components, medium voltage endurance components and high voltage endurance components. The low voltage endurance components are mainly employed in the logic control circuit 116, and an endurance limit for the low voltage endurance components is 1.5-1.8 V. The medium voltage endurance components are mainly employed in the source driver 102, and an endurance limit for the medium voltage endurance components is 5-6 V. The high voltage endurance components are mainly employed in the gate driver 104, and an endurance limit for the high voltage endurance components is 25-30 V. Among the three component categories, the high voltage endurance components require the largest layout area, the most masks and layers in the integrated circuit, and therefore cost the most.
In addition, the high voltage endurance components have to be driven by a high voltage power circuit, such as a charge pump. For example, please refer to FIG. 2, which is a schematic diagram of a high voltage power circuit 20 of the prior art. The high voltage power circuit 20 includes a double voltage charge pump 201 and triple voltage charge pumps 202, 203. The double voltage charge pump 201 converts a supply voltage VDDO of 2.5 V into output voltages V1, V2 of 5 V and 0 V respectively. The triple voltage charge pump 202 converts the output voltages V1, V2 into output voltages V3, V4 of 15 V and 0 V respectively. The triple voltage charge pump 203 converts the output voltages V1, V2 into output voltages V5, V6 of 5 V and −10 V respectively. Since voltage ranges of the triple voltage charge pumps 202, 203 reach 15 V, the triple voltage charge pumps 202, 203 have to be implemented by high voltage endurance components, which is disadvantageous for saving manufacturing time and cost.